## How can you tell a reaction zero order?

$\frac{d[R]}{dt}=-k; [R]=-kt + [R]_{0}; t_{\frac{1}{2}}=\frac{[R]_{0}}{2k}$

Cecilia Jardon 1I
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Joined: Fri Sep 28, 2018 12:16 am

### How can you tell a reaction zero order?

Since rate does not depend on the concentration of the reactant in a zero order rxn then would it be safe to assume that there is no rate law for a zero order rxn?

AnnaYan_1l
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### Re: How can you tell a reaction zero order?

Correct, there is zero order reactions do not have molecularity and do not have a rate law

Kevin Tang 4L
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Joined: Fri Sep 28, 2018 12:28 am

### Re: How can you tell a reaction zero order?

Wouldn't a zero order reaction have the rate law be: rate=k?
It would still have a rate law, it would just be the constant k.

Timothy_Yueh_4L
Posts: 57
Joined: Fri Sep 28, 2018 12:28 am

### Re: How can you tell a reaction zero order?

You could also determine if a reactant is zero order by looking at a table of reactant concentration and rate. If the concentration changes but the rate doesn't, the reactant has a zero order reaction.

Ryan Troutman 4L
Posts: 68
Joined: Fri Sep 28, 2018 12:22 am

### Re: How can you tell a reaction zero order?

There are two ways we can determine this:
If we're given a graph with a negative slope (-k) and a y-axis labelled as [A] (not ln[A] as that would be first order). In addition to this, if we are given a table, and a molar concentration of one of the reactants changes, but the initial rate does not change, then we can determine the reaction is first order since the initial rate was not influenced by the change in molar concentration. Hope this helps :)